By: Charles Leachman, P.G. - LFI Senior Geologist
Vapor Intrusion is the pathway from a subsurface contaminant
source into overlying buildings. The predominant compounds of
concern are volatile organic compounds with benzene, PCE, and TCE
comprising nearly 95% of all vapor intrusion issues.
Impacted soil and groundwater have been regulated
for many years, but currently less than half of our 50 states have
any published regulations or regulatory guidance regarding vapor
intrusion. The US EPA only has Draft Guidance on the
topic. Impacted soil may be particularly detrimental to
construction workers and small children exposed to the specific
areas where impacted soils exist. Impacted groundwater is a
significant concern to humans who may utilize this as a source for
drinking water. Impacted vapors have the potential to
negatively affect all things exposed.
With respect to groundwater issues, the source area of the
problem can usually readily be identified, and there are generally
numerous options available to remediate the impact, including the
use of an alternate supply source. Vapor intrusion tends to
be more difficult to assess, as multiple potential sources within
the home (stored chemicals, cleaners, HVAC emissions, etc.)
complicate the investigation process. Vapor intrusion
remediation can be as easy as installing a fan to as complicated as
laying down an extensive engineered barrier system. Vapor
intrusion investigations are typically performed in office
buildings or residences, which makes ramifications much more
personal to further complicate matters.
Vapor intrusion investigation is often the first item left off
the list when dealing with soil/groundwater plume contamination
scenarios. Lack of knowledge regarding indoor air quality
issues and cost considerations tend to contribute to the omission
of an indoor air/vapor intrusion evaluation.
LFI is a leader in vapor intrusion and vapor intrusion
investigation/mitigation. Our experience includes extensive
assessment work for the Kentucky Department for Environmental
Protection to evaluate petroleum-based soil vapor intrusion source
areas in a fractured bedrock setting; evaluation of private-sector
client issues related to vapor emissions originating from
groundwater affected by chlorinated solvents; and the assessment of
potential vapor intrusion impacts to indoor air in a concession
stand at a city park located near a former dump site. LFI
staff has undergone advanced soil vapor intrusion training at
strategic workshops in Seattle, Los Angeles, and Norfolk. We
have helped educate our peers and the public through vapor
intrusion presentations to the Kentucky Chamber of Commerce and the
Kentuckiana Chapter of Hazardous Material Managers.
While the degree of risk may be debatable, vapor intrusion is
now on the radar of regulators and is here to stay. Contact
Charles Leachman at cleachman@lfienvironmental.com
or (502) 721-5714 for more information or further guidance on these
issues.